1. Field of the Invention
This invention relates to a sewing, and more particularly to a sewing machine having a fabric-edge tracing function.
2. Description of the Prior Art
Fabric-edge tracing sewing machines are already known wherein stitches are formed along a line spaced by a predetermined distance from an edge of a workpiece or work fabric.
One of such fabric-edge tracing sewing machines is disclosed, for example, in Japanese Patent Laid-Open No. 221389/1987 filed by the assignee of the present patent application wherein a fabric-edge detector is controlled so as to follow an edge of a work fabric and stitches are formed at a position spaced by a preset tracing width form an edge of a work fabric.
Conventionally, when a corner of a work fabric is to be traced on a sewing machine, an operator will stop tracing sewing at a lowered position of a needle near a mark applied to a predetermined location of the work fabric at which an angle is to be made by lines of stitches of tracing sewing, and then turn the work fabric in a predetermined direction around the needle whereafter tracing sewing is resumed. In this case, a conventional tracing sewing machine is controlled, when the tracing width upon resuming of tracing sewing is not equal to a preset tracing width, such that the difference in tracing width is gradually corrected in several stitches after resuming of such tracing sewing.
Since a difference in tracing width at a corner of a work fabric is gradually corrected in several stitches as described just above, stitches at the corner will be partially deformed. Consequently, such problems possibly take place that, when a fabric is turned inside out, for example, after plain seaming of a collar end is finished, the angle of the collar end is not formed neatly, that stitches at an angle do not trace an edge of a work fabric accurately so the quality of a product executed by such tracing sewing is reduced.